Liverpool Hospital Emergency Department


Requires discussion with a clinical Toxicologist 

  • Organophosphate poisoning – its use is controversial and is no longer routine o Nerve agent poisoning
  • Antagonist to anticholinesterases such as neostigmine and pyridostigmine, which  are used in the treatment of myasthenia gravis. 


  • 500mg/20mL ampoule 

Dosage and Administration 

  • Bolus dose:
    • In severe poisoning that is unresponsive to other treatments consider 1g pralidoxime iodide (15mg/kg paediatrics to 1g)
  • Infusion:
    • Use 2.5g (5 ampoules) pralidoxime to give a final concentration of 2.5g in  100ml NaCl 0.9%
    • Run at a rate of 250mg/hr (10mg/kg/hr paediatrics)
    • Continue for 12 to 24hours and then review with toxicologist.
    • The infusion may be weaned over 24 to 48 hours, depending on the severity  of symptoms.
    • Cessation of the infusion is based upon clinical testing and mixed plasma  cholinesterase testing. 

Side Effects 

  • Tachycardia
  • Muscle rigidity
  • Dizziness, blurred vision, diplopia, seizure. 
  • Apnoea, Laryngeal spasm 

Pit Falls 

  • Not effective in poisonings due to carbamates
  • Dose adjustment is needed in renal impairment
  • Use with great caution in treating organophosphate overdose in cases of myasthenia  gravis, as it may precipitate a myasthenic crisis.
  • Response will depend on agent, severity and time to treatment